In the previous issue of Critical Care, Sakr and colleagues

[1] reported an epidemiologic study they performed in 24 intensive care units (ICUs) in the Piedmont region of Italy. Th e study documents a lower prevalence of severe sepsis (SS) but a higher ICU mortality in females than in males. Th e study’s results on outcome are puzzling. Most previous studies report either no eff ect of gender or a protective eff ect of being a female. Several confounding factors might account for this result: the number of included patients with SS was small (305, including only 85 females), the period of inclusion during spring and summer induced a seasonal bias with diff erent sources of SS as compared with winter, the percentage of ICU-acquired SS was high (61 % in females), and females with SS were signifi cantly older than males (67.7 versu